Cementing and floating shoe



Sept. 25, 1928.

R. c. BAKER CEMENTING AND FLOATING SHOE Filed -May 11, 1927 LEE.

BY ,jg 44; y am# ATTORNEYS.

Patented Sept. 25, l1928.

.UNITED STATES PATENTl OFFICE.

RE'O'IBEN' C. BAKER,

F COALINGA, CALIFORNIA, ASSIGNOR T0 BAKER CASI'NG SHOE COMPANY, A. CORPORATION OF CALIFORNIA.

CEMENTING AND FLOA'IING SHOE.

Application iled May 11,

This invention relatesl to equipment employed when drilling oil wells.

Hitherto several types of guiding devices have been devised and utilized to guide the 5 lower end of a string of casing into place in 'the hole. One type of guide employed is a hollow spheroidal shell secured to and depending from the lower end of the casing shoe. At the point where it unites with the 1Q casing shoe, the shell agrees in diameter with the shoe but it tapers from this point to its lower end. rIhis' latter end is open so that the fluid in the well will not, to any great extent, resist the lowering of the casing, conse- .quently placing the entire burden of the cas- 5* casing into place.

The employment of these types of guides necessitated separate equipment for cementing the hole after the casing had been posi tioned. To overcome this disadvantage devices known as floating and cementing plugs were produced wherein the opening in the lower end of the shell or guide is closed by means of what is known as a back pressure valve. The pressure of the fluid against this valve when lowering the casing in the hole maintains the valve closed and permits the casing to be floated into place. After the casing is positioned cement is forced down the casing under suiicient pressure to open the valve against the action of its yspring and the external pressure, and discharge into the hole around the casing. After the cementing operation is completed the pressure in the casing is discontinued and the valve is closed by the action of the external pressure in the hole and its spring, excluding the cement in the hole from the casing. After the cement is set the guide and its valve are drilled out and the drilling operation is continued. For

5e this reason the guides and valves were made of friable material.

Such devices as have been described are disclosed in Letters Patent #1,491,915 of the United States issued on April 29, 1924:, to

1927. Serial No. 190,456.

William L. VMcLaine, and Letters Patent #1,559,662 of the United States issued on November 3, 1925, to Reuben C. Baker.

. Under certain circumstances the formation encountered by the guide occasionally damages the valve and plug rendering them inoperative. Likewise, due to the fact that the valve is positioned at the lowermost extremity of the casing, should the casing'be landed on bottom it is impossible to open the valve by internal pressure in the casing. Should the plug and valve become damaged' during the lowering operation the entire weight of the casing is borne by the derrick and frequently necessitates removing the entire casing from the well and refitting a new plug thereto.

It is the principal object of the present invention to generally improve devices of this character by providing improved structures for guiding and floating a casing into place and for cementing after the casing has been positioned.

In carrying out this object into practice I provide a device functioning similarly to the floating and cementing plugs previously described with the exception that the floating and cementing valve structure is novelly combined with the casing shoe and guide so that it will be entirely protected while being low ered into place. Combined with this structure is a fragile guide mechanism for guiding the casing into place. Should this guide be damaged or broken during the lowering operation, the valve structure will sustain the load of the casing so that the latter may be floated into place and will be capable of permitting the cementing operations to be earried out regardless of whether or not the casing is landed on bottom or suspended thereabove. The provision of this device insures that the lowering of the casing will be properly accomplished without the risk of the fioat plug becoming broken or the valve rendered inoperative. The casing shoe is practically ind'estructible while the valve structure and'E the guide are formed of friable-material so that they may be broken out after serving their period of usefulness.

One form' which the invention may assume is exemplified in the following description and illustrated by way of example in the ac companying drawings, in which:

Fig. 1 1s a perspective view 1n section showing one form of the device.

Fig. 2 is a similar view of a second form of the device. A.

Referring more particularly to the accompanying drawings l0 indicates a cylindrical l device known as a casing shoe which is formed of steel and practically indestructible and which is threaded onto the lower end of the casing prior to lowering the latter in a well. In order that it may be threadedly connected with the casing, the casing shoe 10 is interiorly threaded as at 11 so that -it may be threaded on the lower end of a string of casing.

Between this threaded portion 11 and the lower end of the shoe it is formed with a threaded section 12 which is of a different diameter than the diameter of the threaded section 11 which is engaged by the lower end of the casing string.

lIntermediate the two threaded sections 11 and 12 an inwardly projecting annular shoulder 14 is formed. Threaded inthe lower lar 15. This collar 15 is formed with a cylindrical portion 16 exteriorly threaded so that it may be threaded within the lower end of the shoe 10. The bott-om of this collar ispreferably substantially semi-cylindrical and is formed with a central valve openinggl surrounded by a beveled valve seat 18. Above the valve opening within the collar is a bridge 19 constituting a guide for a valve stem 20 secured on a valve 21 which cooperates with the seat to control the passage of fluid through the valve opening.

It is seen that the upper end of the collar is o pen and that the valve closes upwardly against the seat and is normally held in this position by a spring 22 interposed between the bridge and a nut at the upper end of the valve stem. Therefore, fluid pressure above" the valve sufficient to overcome the spring would open the valve but that pressure below the valve will tend to maintain it seated. It will be noticed that in both forms of the device illustrated in the drawings that the lower extremity of the float collar and its valve is above the lower extremity of the casing shoe. The importance of this will be hereinafter pointed out.

The purpose of forming the bottom of the float collar semi-cylindrical is to add strength to the structure so that when floating the casing in a well the'float collar will withstand tremendous pressure without collapsing. The annular shoulder 14 also assists in resisting the pressure and relieving the threads. k

Also threaded within the lower end of the casing shoe is a shoe guide 23. This guide is formed with a hollow spheroidal body p0rtion 24 formed integral with an upwardly extending sleeve 25 which is exteriorly threaded so that the device may be threaded within the end of the casing shoe 10. The' -sleeve 25 is reduced in diameter with respect to the body portion as the latter is of a diameter substantially the same as the exterior diameter of the casing shoe.A Likewise the shoulder intermediate the body portion and the sleeve is tapered to conform with the taper at the lower end of the casing shoe.

In Fig. 1 the lower end of the body portion 24 is shown as closed by means of a plug 26. In this type of construction ports 27 are formed in the casing shoe intermediate the float collar and the sleeve on the shoe guide so that fluid pumped downwardly through the casing and shoe guide under pressure will open the valve and discharge outwardly through these ports. In using a device of this character the well casing may be set in bottom while cement is being forced downwardly through the casing and out through the ports.

In the type of structure shown in Fig. 2, the bottom of the shoe guide is left open and the cement discharged downwardly through the open lower end of the guide.

Due to the fact that the valve structure and the guide must be drilledout after they have served their purposes, it is necessary that they be formed of fragile or friable material such as cast iron. For this reason the guide shoe sometimes becomes broken or damaged during the lowering operation. Therefore, by exposing the guide shoe and placing the fragile valve structure in a protected position within the'end of the indestructible steel shoe, the valve mechanism will always function regardless of whether or not the guide shoe becomes broken:

In prior structures such as illustrated in the McLaine and Baker patents referred to, should the casing meet with an obstruction while being lowered into the well, the valve therein and the plug sometimes became broken causing tremendous damage, because when being broken the entire weight of the well casing is placed upon the derrick equipment and in the instances where the valve became damaged and the casing landed on bottom it was impossible to cement through the structure, necessitating that the entire casing be withdrawn from the well and a new plug fitted thereon.

In the present instance it will be noticed that the float collar carrying the valve 1s positioned at a protecting point within the lower end of the steel shoe, while the exposed part or the guide shoe itself 1s positioned to protect the lower end of the shoe to guide 1t into place. Should this shoe become broken very little damage will be done as the valve mechanism itself will be protected and capa ble of operation when the well casing is positioned in the well. Likewise when it is intended to land the casing on bottom the device shown in Fig. 1 may be used to cement.

Where the casing is not landed the structure illustrated in Fig. 2 may be used and may be cemented through when desired.

In general practice when it is intended to cement, the structure illustrated in Fig. 1 is used as the casing may be placed Jon bottom during the cementing operation. nWhen merely desiring to float the casing into place, the device shown in Fig. 2 is'used, although itis possible to cement through this structuren if desired.

From the -foregoing-it is obvious that I have provided a combined floating and cementing plug for well casings which will not become damaged during the lowering of the casing into the Well, which will permit tion by Kthose skilled in the art without departing from the spirit of the invention, as dened in theappended claim.

Having thus described my invention, what I claim and desire to secure by Letters Patent A cementing and floating plug for well casings comprising a cylindrical shoe formed of comparatively indestructible material, a. valve structure including a valve cage threaded into said shoe, said valve cage having an opening formed therethrough, a downwardly opening valve controlling said opening,4 a guide member threaded into the bottom of said shoe and depending downwardly therefrom, the valve structure and guide being formed of friable material whereby they may be broken out after use, said cylindrical shoe having openings formed therethrough intermediate the valve structure and the guide to permit lui'd passing through the valve structure to discharge.

' f REUBEN C. BAKER. 

